Abstract: An uninterruptable power supply device includes a mains commutation conductor, a voltage intermediate circuit converter having an associated control device, an output filter comprising a transformer with high leakage inductance and filter capacitors, a mains reset device having an associated control device, and a manual bypass switch. A frequency converter (32) from drive technology is used as the converter, an input filter is connected upstream of this frequency converter, and a battery coupling apparatus is connected to its DC busbar connections. In this way, it is possible an uninterruptable power supply device may be provided which uses the technical and economic synergies from drive technology using commercially available components from drive technology and using UPS-specific components.